Standing Wave/ Resonanace problem PLEASE HELP

Ok. I've tried to answer this problem so many times now, but I just cant get it. Here it is:

A child's toy called a twirler, consists of a tube (like a hose, which is spun
in a circle above one's head. It is noted that at certain rates of rotation,
sounds of definite pitch are heard. What is the source of the sound? what are
the resonance effects? What is the relationship between pitch and rate of
rotation...?

Ok. I've tried to answer this problem so many times now, but I just cant get it. Here it is:

A child's toy called a twirler, consists of a tube (like a hose, which is spun
in a circle above one's head. It is noted that at certain rates of rotation,
sounds of definite pitch are heard. What is the source of the sound? what are
the resonance effects? What is the relationship between pitch and rate of
rotation...?

Thank You in advance

It will make a difference in the pitch if the tube is open on both ends or closed on the end being held. I assume it is open at both ends. You need to look at standing waves in a pipe, and think about two possible effects from twirling the tube. 1) Will the pressure in the tube change when it is being twirled? If it does, that will affect the speed of sound in the tube and that will affect the resonant frequency. 2) The doppler effect. The sound source will be moving relative to an observer hearing the sound from a tube someone else is twirling.